This application claims the priority of German patent document 196 49 739.6, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a release device for a retaining bolt that can be pretensioned in the direction of its lengthwise axis. The device releases the retaining bolt from a pretensioned deployment position.
German patent document DE-AS 28 53 070 discloses a release device of this kind, in which the retaining bolt is held in its pretensioned position by the nose of a locking pin. After being released, the locking pin is pushed back by a blocking element due to the pretensioning of the retaining bolt. In an embodiment currently in use, the locking pin is separated pyrotechnically. In this known device, only a limited holddown power is possible, and pyrotechnic separation of the locking pin poses problems in spacecraft due to shock and the creation of particles.
The object of the present invention is to permit higher holddown forces in a release device of the type mentioned above.
Another object of the invention is to accommodate the parts of the device in a small space. Still another object of the invention is to eliminate the need for pyrotechnics.
These and other objects and advantages are achieved by the release device according to the invention, in which the end of a retaining bolt which is used to hold down, for example, the solar panels of a solar generator, is screwed into an opener which consists of two halves that are separable along a longitudinal axis of threads which hold the screwed in end. The two halves of the opener are held together by a coil of wire which is anchored by fuse elements at both ends thereof. To release the retaining bolt, the wire coil is released by the fuse elements, permitting the halves of the opener to separate.
The device according to the invention has a number of advantages. The holddown power can exceed 13,000 N. Release by opening the wire coil using fuse wires takes place at both ends of the wire coil, and is therefore redundant. No pyrotechnic triggering energy is necessary, no parts are destroyed, and thus no particles are released that contaminate the chamber. The device is given a compact design, and one practical application has a diameter of only 56 mm and is 27 mm high, weighing 0.084 kg. The device can be used universally in a temperature range of .+-.150.degree. C. Because pyrotechnics are eliminated, no specially trained personnel are required.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.